An electric generator transforms mechanical energy into electrical energy. In general, an electric generator includes a rotatable rotor positioned within a stationary stator. Rotor windings are energized to generate a magnetic field. Upon actuation of the rotor, the rotating magnetic field is coupled into stator windings positioned on the stator. In this manner, an electromotive force (EMF) is induced in the stator windings such that the electric generator may supply rated voltage and power to a load.
Typically, the rotor includes a magnetic core material constructed from a grade of electrical steel that retains a fraction of the magnetic field or flux when the generator is turned off. This residual magnetism influences generator operation under start-up conditions. However, the magnitude of residual magnetism retained by the rotor is degenerative, therein potentially effecting start-up characteristics of the electric generator.